Conventionally, an electrically heated catalyst (hereinafter sometimes called EHC) has been developed as an exhaust gas purification catalyst provided in the exhaust gas passage of an internal combustion engine. This catalyst is heated by a heating element that generates heat when electrically conducted.
In an EHC, an insulating member for insulating electricity is provided between a heating element, which generates heat by electric conduction, and a case in which the heating element is stored. For example, for use with an EHC, Patent Literature 1 discloses a technology for providing an insulator mat between a carrier, which generates heat by electric conduction, and a case in which the carrier is stored. Such an insulating member, if provided, can prevent a short circuit between the heating element and the case.
Patent Literature 2 discloses a technology for supplying secondary air to the EHC with the EHC heated to an activation temperature. This is accomplished by starting the operation of an electric air power pump after the operation of the EHC is started at a cold start time of an internal combustion engine.
Patent Literature 3 discloses a technology for use in a hybrid system. This technology controls electric conduction to the heater of an air-fuel sensor, provided in the exhaust gas passage of an internal combustion engine, while the operation of the internal combustion engine is stopped.